I'm trying to reduce the current draw and heat when moving a nema 17 with an a4899. I have tried setting the reset, sleep and enable to low when the motor isn't being used and I set them to high when they need to be used - all of these tests have been done by changing the pins individually. When the motor starts moving, there is a slight additional movement to the steps I send, which makes the motor never stop at the right location. Of course, with several movements, the total offset is quite significant. If I jump the reset and sleep pins, everything runs perfectly, but then there's always a current draw and there's an increase in the temperature of both the driver and the motor. What can I do to resolve this issue?
If there is an Enable pin on the stepper drive You might set it to inactive to cut heating in the stepper.
Puting the controller to sleep is wrong as the driver will still run.
Make sure the current setting in the driver is within the motor limits.
I think your problem may be that the motor stops at a stable position with the coils energised, but when the current is switched off by disabling the driver the rotor jumps to an adjacent position that is stable with no current. Depending on the state of the driver when re-enabled it may do something similar. Modern drivers designed more for CNC don't switch of the coil current completely but just reduce it so the motor stays in the same position. The A4988 (which is what I think you are probably using) is a nice device but rather old - maybe a more modern driver would be better? DRV8825 is good (though I don't know how it handles reset), or maybe one of the Trinamic devices?
Are you really worried by the heat? Steppers are designed to cope with quite high temperature (uncomfortable to hold) and the driver should cope is it has a heatsink.
The max current was a bit higher. After I posted, I checked the vref again and lowered it a bit, as suggested, and that helped quite a bit. I think I must have moved the potentiometer and forgot I did. Thank you!
I'm more worried about the power draw when idle, tbh. I was hoping turning the motor off would do the trick. I'll probably give driver you suggested a try. Thank you!